Tracer bullet



9 N. K. TURNBULL 1 3 TRACER BULLET Filed July 16, 1942 N n r in an K -T urnbull Patented Aug. 7, 1945 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention deals with a tracer bullet and particularly relates to a tracer bullet having a trace which is extinguished at a definite point.

In using tracer ammunition in aircraft it is a decided advantage to have a tracer which goes out at a definite point, so that the pilot can use the trace as a yard stick in judging distance. For instance the .30 cal. aircraft machine gun is not of much value when fired at targets more than 600 yds. away. which goes out at a definite point, say 600 yards, he can tell whether he can deliver effective fire on the target. In the past it has been attempted to provide such a bullet by carefully regulating the amount of tracer composition which is loaded into the bullet, This has not always been successful for the reason that after the tracer composition has been consumed a mass of incandescent ash frequently remains behind. This incandescent ash which glows for a variable period accounts for the undesirable characteristics of the normal tracer bullet.

It is therefore an object of this invention to provide a tracer bullet in which the trace is extinguished at a definite and determinable time. It is a further object of this invention to provide a tracer in which no incandescent ash is left when the tracer composition is consumed so that the tracer will not show beyond a, certain range.

The drawing, in cross-section, illustrates one embodiment of the present invention. According to this drawing there is shown a projectile having a jacket I which may be of gilding metal. The bullet has an ogive portion which may be filled with a suitable slug 2 of lead, lead alloy, steel or other suitable material. The tracer composition 3 occupies the space adjacent the slug and on top of this a suitable igniter composition 4 is placed. To ex ell the incandescent ash after the tracer composition is consumed an explosive pellet 5 is provided. This is placed in contact with the slu so that it will not be detonated until substantially all of the tracer composition is consumed. When the explosive pellet is detonated all of the ash remaining in the bullet is expelled, so that there is no afterglow.

One convenient explosive pellet is a standard cal. .50 primer which is assembled in the usual If the gunner has tracer ammunition way except that the anvil may be omitted. The cup 6 may be inserted so that the open end is towards the slug. In this manner the cup tends to protect the explosive pellet and to dissipate the heat from the burning tracer composition. Thus, a slight delay is provided, so that substantially all of the tracer will be consumed before the p t is detonated. It is not necessory to use a metal cup to contain the explosive charge, as a compressed pellet can be used as well. Suitable explosive compositions include, besides the usual primer mixtures, black powder, smokeless powder, T. N. T. (trinitrotoluene) and the like.

This invention can be used in conjunction with a delayed action igniting charge to produce a trace which will start some distance from the gun and which will be extinguished at a determinable point.

To accuratelyplace the explosive pellet and to facilitate loading, the slug 2 may have a small depression I at its base to at least partially receive the pellet.

I claim:

1. In a tracer projectile comprising a main body 2; portion, a tracer composition, an element of explosive substance adjacent the inner end of the tracer composition remote from the point of ignition thereof, and an element in said main body portion forward of said explosive substance comprising a fixed, gas-impervious surface whereby to provide a reaction thrust relative to the remnants of said tracer charge on initiation of said explosive substance by said tracer composition to expel said remnants from said body portion.

2. The tracer projectile of claim 1 in which the explosive substance is an explosive chosen from the group consisting of black powder, smokeless powder and T. N. T.

3. In a tracer projectile a jacket having an ogive portion, a metal slug at least partially filling the ogive portion, a charge of tracer composition lying adjacent to the slug and a small amount of an explosive substance lying between the slug and the tracer composition.

4. The tracer projectile of claim 3 in which the metal slug has a depression to at least partially receive the explosive substance.

5. The tracer projectile of claim 3 in which the explosive charge is held in a small metal cup having an open end, the open end being turned away 

